That's just the reference compiler informing you that not all language features of ver 410+ are available for validation. It will try and check what it knows about, only. You'll get the same warning on NVidia and Intel cards as well.
The shader issue you are having on AMD is real (see the clip distance thread on the forum for more details), but the warning is nothing to worry about. I'm using it with 430 and 440 shaders.